1. The Field of the Invention
The present invention relates to a light filtering system for creating stereoscopic images or enhancing three-dimensional images. More particularly, the present invention relates to a method for imparting a stereoscopic quality to a two-dimensional color television image or like video image, or to enhance an existing three-dimensional image. In a further aspect, the present invention also relates to the eye wear which can be used in accordance with the system.
2. The Prior Art
The prior art includes systems developed to convert a two-dimensional movie or television image to a stereoscopic image. Most of the conventional systems involve a modified two-dimensional image. Generally, these systems require the projection of two separate, shifted images using light of two different colors or polarizations. Specialized eye wear then separates the images, transmitting one image to one eye and the other image to the other eye. The dual image tricks the brain into perceiving depth.
Another method of creating a stereoscopic effect which does not require special images, uses eye wear with "neutral density" filters. In this type of eye wear, the lens for one eye is darker than the lens for the other eye. The nerves of the viewer do not transmit the darker image to the brain as fast as the lighter image. This causes a time delay between when the brain receives each image. This time delay between the light and dark images, commonly called the Pulfrich Effect, creates the illusion of a single stereoscopic image.
These methods have been described in or have been the subject of various patents. For example, U.S. Pat. No. 1,182,280, to J. Kennedy, discloses an early device for creating a stereoscopic effect. The device has picture cards that are rotated on a wheel. Each of the cards has a double image, preferably with an image in red superimposed on the same in green or vice versa. Further, the device has a viewing plate with colored lenses. Green and red are said to be proven as colors for the lenses.
U.S. Pat. No. 1,498,743 to Macy discloses making a three-dimensional image with a two color, double printed stereographic picture. The preferred colors are red and green. To see the picture, the viewer looks through a pair of glasses provided with a green lens and a red lens.
U.S. Pat. No. 1,548,262 to Freedman teaches the manufacture of bi-colored eye glasses. The glasses are said to have twin lenses of transparent or translucent material which are of different colors or tints, as for instance one of blue or green and one of red or orange color. The spectacles are said to have utility mainly in viewing pictures whereby certain novel effects are attained.
A cinematographic device for creating a three dimensional image is disclosed in U.S. Pat. No. 1,745,107 to Mendoza. The device has a transparent screen with successive divisions of green and red color. The screen is moved rapidly in front of a movie projector. The viewer is said to watch the projected movie with glasses having a red lens and a green lens.
U.S. Pat. No. 4,134,644 to Marks et. al. describes a system for creating three dimensional images with a stereoscopic camera system and specially colored glasses. One eye is covered by a green filter, while the other eye is covered with a red and blue filter (magenta) filter. The filters have complementary band passes and band stops.
German Patent Document No. DT 3343-781 to Gronenborn discloses a pair of glasses for creating a three dimensional image from a normal television image. The glasses have prisms on each lens for breaking the incident light into its individual colors. The lenses themselves are color filters, one lens being red while the other lens is green.
German Patent Document No. DT 3428-038 is similar to DT 3343-781. According to Document No. DT 3428-038, however, one lens cuts off the green end of the spectrum while the other lens cuts off the red end of the spectrum.